Scanning electron microscopy (SEM) reveals a concave structure, called the adhesive disk, that covers much of the ventral surface (Fig. A). Also evident are a pair of ventral flagella (VF) emerging into the ventral groove (VG) and a ventro-lateral flange (VLF). Transmission electron microscopy (TEM) reveals a close association between the adhesive disk and the brush border of the intestinal epithelium and the outer rim of the adhesive disk, called the lateral crest, is in direct contact with the microvilli (Fig. B). The adhesive disk has a striated appearance in cross-section and higher magnification (Fig. C) reveals structures called microribbons (mR) in close association with microtules (mT). These microribbons + microtubules are arranged in concentric rows that form a small circular spiral. (Note spiral shape of adhesive disk in Fig. A.) Trophozoite detachment leaves a dome-shaped imprint in the brush border (Fig. D) suggesting that contractile forces are involved in attachment.